My question is about the word 'Hammer' in colloquial and idiomatic usage.
I have heard this word used in three ways in German:
Das ist der Hammer (to indicate that something is cool or awesome)
Das ist der Hammer (to indicate that something was poorly done or needs improvement, for example a professor saying this to a student about a test)
Und jetzt kommt der Hammer... (Said by a professor when reading a text to indicate that the following word, clause, or sentence was important or perhaps interesting)
Are these all valid idiomatic or colloquial uses of this word?
Have I correctly interpreted and explained each situational meaning in my examples?
Are there any other meanings of this word that I have not listed? This part of the question may be disregarded if this makes the scope to broad to answer.